1. Field of the Invention
The present invention relates to an operating method for a working area comprising a robot enslaved to a bending press for working metal sheets.
2. Related Art and Other Considerations
It is known that the process of cold-bending thin metal sheets has been performed for years with vertical hydraulic bending presses enslaved to manual operators or with completely automatic programmable bending presses. Recent advances in the field of electronic controls have led to the introduction in the sector of working thin metal sheet of bending presses enslaved to anthropomorphous robots provided with an arm having a plurality (five or more) of rotational joints, one or more sliding joints, and a grasping member (hand).
Anthropomorphous robots are programmed with specific instructions that allow the hand to be led through programmable points of space with attributes of speed, acceleration and methods of interpolation that can be defined by the programmer/user. Such instructions for part of specific programming languages that also contemplate the definition of variables, of vectors, of control structures of the type "if . . . then" and of functions. The variables can also be associated with electrical input/output signals to obtain functions of programmable logic.
One of the more complex operations of these robots is their initialization by means of the definition of variables of position that allow the description of the trajectory in space of the arm and of the grasping member to be made. Generally, the initialization of the anthropomorphous robots is executed with a method of execution called "self-learning".
Self-learning allows the initialization of the variables of position, defined in the program of the robot's working cycle, by means of the storage of encoder data, associated with the arm and with the hand under the control of an operator, that leads the robot to the selected point. Generally, robot manufacturers provide a programming language for the sequence of actions to be carried out and a self-learning method for the initialization of the data that can be used for very generic applications. The adaptation of the sequences and of the data to a specific work have the disadvantage that, in the case of a work of bending metal sheets, they require times ranging from four hours to eight hours or more. This time of adaptation is certainly negligible in the case of large production lots but it does translate into a highly onerous "down time" in the case of hydraulic bending presses for thin metal sheets used, as is often the case, for the production of small lots.
Moreover, the self-learning step also requires specific competences on the part of the operator, but this type of operator is frequently missing in the firms that produce small lots or, in any case, his possible presence involves a further increase in costs.
Another drawback is in the fact that the self-learning step has to take place within the field of action of the robot. In fact, in order to initialise the robot, an operator has at his disposal a portable keyboard (teach pendant or control by wire). But, in order to drive the robot to the operating positions with adequate accuracy and to check that it does actually take up the pre-established final positions with respect to the press, the operator is generally obliged to inspect at very close range the positions actually assumed by the robot and this takes him inside the field of action of all the components in motion of a working area and, thus, in conditions of serious danger.
Moreover, the self-learning is often not sufficient to program the working cycle suitable for producing a new bent metal sheet and it has to be integrated with changes in the previously programmed operative sequences.
Generally, since staff have a limited competence, they modify the robot's operative sequences in a somewhat inefficient manner due to their limited familiarity with the subject.
An object of the present invention is an operating method for a working area comprising a robot enslaved to a bending press that allows the above-mentioned disadvantages to be overcome, totally eliminating the steps of self-learning and of modifying the robot's operative sequences whenever it is necessary to produce a new finished bent metal sheet.